Android source builds fail at configureBuildForHermes since facebook/hermes moved to meta/hermes #59587

Description

Since facebook/hermes moved to meta/hermes (2026-10-28), building React Native from source on Android fails at :packages:react-native:ReactAndroid:hermes-engine:configureBuildForHermes.

Cause:

• downloadHermes fetches https://github.com/facebook/hermes/tarball/<tag>. That URL now redirects (301) to meta/hermes, so the download itself still works.

• GitHub names a tarball's top-level folder <owner>-<repo>-<sha>, so it is now meta-hermes-<sha>/ rather than facebook-hermes-<sha>/:

  $ curl -sL https://github.com/facebook/hermes/tarball/hermes-v260318099.0.2 | tar -tz | head -1
  meta-hermes-4188b63/
  

• unzipHermes only flattens entries that start with facebook-hermes-. So Hermes is extracted to sdks/hermes/meta-hermes-<sha>/, and CMake finds no CMakeLists.txt in sdks/hermes.

Who's affected: anyone building React Native from source on Android, e.g. via includeBuild + dependencySubstitution or Expo's buildReactNativeFromSource, whenever Hermes has to be downloaded again (CI, fresh clones, fresh node_modules). Apps using the prebuilt artifacts don't download Hermes, so they're unaffected. main (as of dee5bb5) and 0.88-stable both still have the facebook-hermes- check.

Proposed fix: strip the tarball's single top-level folder unconditionally, the same way the folly, fmt and fast_float download tasks in ReactAndroid/build.gradle.kts already do. That no longer depends on the repo owner and behaves the same for the old tarballs. Pointing the download URL at meta/hermes would also stop relying on the redirect. I'll open a PR.

(Not the same as #59514, which touches the same file but is about a stale CMake cache after the source directory moves.)

Steps to reproduce

1. Clone https://github.com/mozzius/hermes-tarball-repro. It's the community reproducer template (React Native 0.88.1) with one change: android/settings.gradle builds React Native from source.
2. Run cd ReproducerApp && yarn && cd android && ./gradlew :app:assembleDebug -PreactNativeArchitectures=arm64-v8a.
3. The build fails within about 30 seconds at configureBuildForHermes (log below).

The repo's fixed branch applies the proposed change with patch-package. With it, unzipHermes, configureBuildForHermes, buildHermesC and prepareHeadersForPrefab all pass, and CMakeLists.txt lands directly in sdks/hermes.

React Native Version

0.88.1

Affected Platforms

Runtime - Android, Build - MacOS

Output of npx @react-native-community/cli info

System:
  OS: macOS 27.0.1
  CPU: (14) arm64 Apple M4 Pro
  Shell:
    version: 5.3.20
    path: /opt/homebrew/bin/bash
Binaries:
  Node:
    version: 24.22.1
  Yarn:
    version: 1.22.22
  npm:
    version: 11.19.1
  Watchman:
    version: 2026.10.19.00
SDKs:
  Android SDK:
    API Levels:
      - "35"
      - "36"
      - "37"
    Build Tools:
      - 36.0.0
      - 37.0.0
IDEs:
  Android Studio: 2026.1 AI-261.26222.65.2614.16379836
Languages:
  Java:
    version: 17.0.20.1
npmPackages:
  "@react-native-community/cli":
    installed: 20.2.0
    wanted: 20.2.0
  react:
    installed: 19.3.0
    wanted: 19.3.0
  react-native:
    installed: 0.88.1
    wanted: 0.88.1
Android:
  hermesEnabled: true
  newArchEnabled: true

Stacktrace or Logs

> Task :react-native:packages:react-native:ReactAndroid:hermes-engine:downloadHermes
> Task :react-native:packages:react-native:ReactAndroid:hermes-engine:unzipHermes

> Task :react-native:packages:react-native:ReactAndroid:hermes-engine:configureBuildForHermes FAILED
CMake Error: The source directory ".../ReproducerApp/node_modules/react-native/sdks/hermes" does not appear to contain CMakeLists.txt.
Specify --help for usage, or press the help button on the CMake GUI.

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':react-native:packages:react-native:ReactAndroid:hermes-engine:configureBuildForHermes'.
> Process 'command '.../cmake/3.30.5/bin/cmake'' finished with non-zero exit value 1

BUILD FAILED in 30s

MANDATORY Reproducer

https://github.com/mozzius/hermes-tarball-repro

Screenshots and Videos

No response